Fig. 1

Alterations of tidal volume (TV, mL) were visually depicted for the initial, middle, and late periods of the recording, demonstrating the trend over recording time. The solid circle and thick line represent the overall trend of all sites, while the trend of individual sites is illustrated with different symbols and thin lines. (Abbreviations: TV-initial, TV-mid, and TV-late represent tidal volume of the initial, middle, and the late period of the recording)